118 lines
2.8 KiB
C++
118 lines
2.8 KiB
C++
// Boost.Geometry
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// Copyright (c) 2020, Oracle and/or its affiliates.
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// Contributed and/or modified by Vissarion Fysikopoulos, on behalf of Oracle
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// Licensed under the Boost Software License version 1.0.
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// http://www.boost.org/users/license.html
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#ifndef BOOST_GEOMETRY_STRATEGY_CARTESIAN_PRECISE_AREA_HPP
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#define BOOST_GEOMETRY_STRATEGY_CARTESIAN_PRECISE_AREA_HPP
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#include <boost/mpl/if.hpp>
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//#include <boost/geometry/arithmetic/determinant.hpp>
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#include <boost/geometry/core/access.hpp>
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#include <boost/geometry/core/coordinate_type.hpp>
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#include <boost/geometry/core/coordinate_dimension.hpp>
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#include <boost/geometry/strategy/area.hpp>
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#include <boost/geometry/util/select_most_precise.hpp>
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#include <boost/geometry/util/precise_math.hpp>
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namespace boost { namespace geometry
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{
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namespace strategy { namespace area
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{
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/*!
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\brief Cartesian area calculation
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\ingroup strategies
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\details Calculates cartesian area using the trapezoidal rule and precise
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summation (useful to increase precision with floating point arithmetic)
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\tparam CalculationType \tparam_calculation
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\qbk{
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[heading See also]
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[link geometry.reference.algorithms.area.area_2_with_strategy area (with strategy)]
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}
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*/
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template
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<
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typename CalculationType = void
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>
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class precise_cartesian
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{
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public :
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template <typename Geometry>
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struct result_type
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: strategy::area::detail::result_type
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<
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Geometry,
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CalculationType
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>
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{};
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template <typename Geometry>
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class state
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{
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friend class precise_cartesian;
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typedef typename result_type<Geometry>::type return_type;
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public:
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inline state()
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: sum1(0)
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, sum2(0)
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{
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// Strategy supports only 2D areas
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assert_dimension<Geometry, 2>();
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}
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private:
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inline return_type area() const
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{
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return_type const two = 2;
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return (sum1 + sum2) / two;
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}
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return_type sum1;
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return_type sum2;
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};
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template <typename PointOfSegment, typename Geometry>
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static inline void apply(PointOfSegment const& p1,
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PointOfSegment const& p2,
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state<Geometry>& st)
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{
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typedef typename state<Geometry>::return_type return_type;
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auto const det = (return_type(get<0>(p1)) + return_type(get<0>(p2)))
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* (return_type(get<1>(p1)) - return_type(get<1>(p2)));
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auto const res = boost::geometry::detail::precise_math::two_sum(st.sum1, det);
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st.sum1 = res[0];
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st.sum2 += res[1];
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}
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template <typename Geometry>
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static inline auto result(state<Geometry>& st)
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{
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return st.area();
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}
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};
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}} // namespace strategy::area
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_STRATEGY_CARTESIAN_PRECISE_AREA_HPP
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